Field of the Invention
The invention relates generally to a driving method of a display, and more particularly, to a driving method of an electrophoretic display capable of enhancing the color saturation, brightness, contrast ratio, and image updating time of a displayed image.
Description of Related Art
In recent years, as display technologies are pursued vigorously, devices such as the electrophoretic display, the liquid crystal display, the plasma display, and the organic light emitting diode display have been commercialized and applied in display apparatuses of various size and shape. With the popularization of portable electronic devices, flexible displays (e.g., e-paper and e-book) have received market attention. Typically speaking, e-papers and e-books adopt electrophoretic display technologies for displaying an image. Taking the e-book for example, a sub-pixel therein is mainly formed by different colors (e.g., red, green, blue) of electrophoretic mediums and white charged particles mixed in the electrophoretic mediums. The white charged particles are manipulated by external driving, such that each pixel respectively displays black, white, red, green, blue, or colors adjusted at different levels.
Generally speaking, a conventional driving method of the electrophoretic display divides the writing duration into at least four periods: a pre-charge period, a gray-level write period, a reset period, and a frame follow period. Moreover, in different periods, corresponding voltages are applied to a data line and a common electrode of the electrophoretic display, so as to generate voltage differences in the data line and the common electrode to drive the display particles. In the pre-charge period, a positive voltage difference or a negative voltage difference is formed between the data line and the common electrode in order to increase the charge of the display particles (e.g., black, white, or other colors). In the gray-level write period, positive or negative voltage difference is formed between the data line and the common electrode according to the polarity of the display particles, so that display particles gradually appear visible. Moreover, the visibility of the display particles is proportional to an apply time of the aforesaid voltage difference. Accordingly, a gray-level distribution in a particular color field (e.g., a white image or a black image) is adjusted. In the reset period, the positive or negative voltage difference is formed between the data line and the common electrode, so that display particles emerge or immerse towards the boundaries to clear away afterimages. In the frame follow period, zero voltage difference is formed between the data line and the common electrode so that the display particles maintain their current positions.